The present invention relates to the field of ore processing. More particularly, the invention relates to the beneficiation of naturally occurring ores consisting essentially of titania and silica compounds and uses of these processed ores. By the methods of the present invention, from these ores, one may isolate high purity unique TiO2 compounds. These compounds may be used directly in many of the products and processes that traditional sources of TiO2 are used without being subjected to more traditional and burdensome processes such as the chloride and sulfate processes. Because the TiO2 compounds of the present invention are produced more economically than TiO2 is typically produced, these TiO2 compounds offer attractive options for manufacturing TiO2 containing products.
Naturally occurring ore that contains titania compounds, such as TiO2, typically is not suitable for direct extraction of pigmentary and subpigmentary sized TiO2 particles. The physical and chemical compositions of most ores that contain titania, for example, ilmenite, require that ore be processed via either the xe2x80x9cchloridexe2x80x9d or the xe2x80x9csulfatexe2x80x9d methods in order to convert the titanium compounds found in the ore into intermediate chemical forms, such as titanium tetrachloride or titanyl sulfate, prior to conversion into particles of TiO2 useful for industrial applications. Thus, most ores do not lend themselves to direct extraction and incorporation into products.
Processing ore via the xe2x80x9cchloridexe2x80x9d and xe2x80x9csulfatexe2x80x9d methods is both costly and labor intensive, requiring significant capital investment in equipment and personnel. Consequently, there is a need to develop less expensive methods for obtaining commercially useable TiO2 and TiO2 concentrates.
Certain ore deposits, for example, ore deposits in Peru near the town of Tacna on the Peruvian-Chilean border approximately 86 km to the northeast of Tacna, contain titania particles of varying sizes and crystal aggregations in a matrix of essentially crystalline silica. These titania particles contain both rutile crystals and anatase crystals, and typically are approximately 40% rutile crystals and 60% anatase crystals, but they may contain between 15-50% rutile and 50-85% anatase crystals.
Traditional ore processing and separation techniques are not efficient in separating the titania and silica components of this type of ore. This type of naturally occurring ore, regardless of where it is found in the world, is referred to herein as xe2x80x9cTacna-type ore.xe2x80x9d The amount of titania and silica, as well as the other parameters of Tacna-type ore are more fully described in the detailed description below.
In order to separate the titania particles from the silica matrix of Tacna-type ore, a series of processing steps were needed. Once Tacna-type ore is processed, a compound that contains a greater percentage of the TiO2 compound may be isolated. The phrase xe2x80x9cTiO2 compoundxe2x80x9d as used herein refers to any ore that has been processed from Tacna-type ore so as to increase the relative percentage of titania to other particles to above about 50% by weight.
The TiO2 compounds of the present invention thus offer novel and efficient methods of processing TiO2 for use in many applications in which TiO2 is currently used, including in paper, plastics and coating applications, as well as in other applications such as catalysts and sunscreens. Because the processes that were developed are more cost effective than traditional processing techniques, less expensive products containing TiO2 may be produced.
The present invention relates to processes for obtaining TiO2 compounds from Tacna-type ore, the methods for using these TiO2 compounds, and these TiO2 compounds themselves.
Under one embodiment, the present invention provides a process for obtaining the TiO2 compounds from Tacna-type ore that may be used directly in many applications without the use of the burdensome chloride or sulfate process. This method comprises:
a. grinding a Tacna-type ore to form ground ore having particles of a size suitable to form an aqueous slurry;
b. combining the ground ore, water and a separating agent so as to form an aqueous slurry of constituents; and
c. separating the constituents of the aqueous slurry to isolate the TiO2 compounds.
The separating step may be accomplished by a number of methods, including selective flocculation and biphasic extraction, such as with polyglycolic compounds. These methods may be used alone or in combination.
The TiO2 compounds that have been processed by this method may be used in a variety of applications. For example, the TiO2 compounds may be further processed in a manner so as to isolate the ultrafine sized titanium dioxide particles for direct use in applications such as sunscreens and automobile catalysts. Further, the TiO2 compounds may be used directly in many paper, plastics and coatings applications. Moreover, the TiO2 compounds may be used alone, or blended with other ores that are not Tacna-type ores and used as feedstock in either the sulfate or the chloride processes for the production of TiO2 pigments that can be used in papers, plastics and coatings applications.
Under another embodiment, the present invention relates to the isolated and purified TiO2 compound itself, which is formed by the beneficiation of Tacna-type ore. These TiO2 compounds consist essentially of silica and titania wherein the titania is at least about 50% by weight of the TiO2 compound. The titania consists essentially of rutile and anatase crystals, wherein the weight of the rutile crystals is preferably between about 30% and about 50% of the total titania.